Files
tippecanoe/geobuf.cpp
T
Claude 7127e49c86 Replace the Grisu2 float formatter with a C++ port of rsc/fpfmt
Tippecanoe formatted every double it wrote through milo::dtoa_milo, a
vendored Grisu2. Grisu2 is fast, but it guarantees neither the shortest
digit string nor the correctly rounded one: it only guarantees that what
it prints parses back to the value it came from. In practice it prints a
digit more than necessary about 0.16% of the time, and picks a neighbor
of the correctly rounded digits about 32% of the time.

This ports Russ Cox's fpfmt (https://github.com/rsc/fpfmt) to C++ in
fpfmt/ and formats through it instead. fpfmt is both shortest and
correctly rounded, and it is faster:

  full std::string formatting     Grisu2      fpfmt   speedup
  random bit patterns          156.62 ns   66.83 ns     2.34x
  geo coordinates              124.07 ns   58.62 ns     2.12x
  short decimals                69.37 ns   49.16 ns     1.41x
  small integers                44.18 ns   38.06 ns     1.16x

  digit generation only           Grisu2      fpfmt   speedup
  random bit patterns           90.07 ns   20.81 ns     4.33x
  geo coordinates               80.64 ns   20.18 ns     4.00x
  short decimals                55.61 ns   21.90 ns     2.54x
  small integers                40.23 ns   22.50 ns     1.79x

(Intel Xeon @ 2.80GHz, g++ 13.3 -O3. `make fpfmt-bench` reproduces this,
and `./fpfmt-bench -check` reruns the correctness sweep, which is why
milo/dtoa_milo.h is kept even though nothing links it any more.)

The port is deliberately literal, so it can be diffed against fpfmt.go.
Its Short() agrees bit for bit with the Go original's on 445,640 values
covering powers of ten, small integers and reciprocals, subnormals, and
random bit patterns. Over 38.5 million values, fpfmt::dtoa always round
trips, is never longer than Grisu2's output, and is shorter 61,329 times.

Output is otherwise formatted exactly as before, including the choice
between plain and exponential notation, so 26 expected test outputs
change: some numbers lose digits (-26.170044999999999 becomes
-26.170045), and some have a corrected final digit (9.823748927348929e+55
becomes 9.823748927348928e+55). Every changed token was checked to parse
back to the identical double; none of the values themselves moved.

milo/milo.h, whose only job was to declare the C shim jsonpull calls, is
replaced by fpfmt/fpfmt.h, and the shim is renamed dtoa_shortest.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014wJRAuhMninQE4wK2TUfuZ
2026-08-31 00:22:35 +00:00

582 lines
13 KiB
C++

#include <stdio.h>
#include <string>
#include <limits.h>
#include <pthread.h>
#include "mvt.hpp"
#include "serial.hpp"
#include "geobuf.hpp"
#include "geojson.hpp"
#include "projection.hpp"
#include "main.hpp"
#include "protozero/varint.hpp"
#include "protozero/pbf_reader.hpp"
#include "protozero/pbf_writer.hpp"
#include "fpfmt/fpfmt.hpp"
#include "jsonpull/jsonpull.h"
#include "text.hpp"
#include "errors.hpp"
#include "thread.hpp"
#define POINT 0
#define MULTIPOINT 1
#define LINESTRING 2
#define MULTILINESTRING 3
#define POLYGON 4
#define MULTIPOLYGON 5
struct queued_feature {
protozero::pbf_reader pbf{};
size_t dim = 0;
double e = 0;
std::vector<std::string> *keys = NULL;
std::vector<struct serialization_state> *sst = NULL;
int layer = 0;
std::string layername = "";
};
static std::vector<queued_feature> feature_queue;
void ensureDim(size_t dim) {
if (dim < 2) {
fprintf(stderr, "Geometry has fewer than 2 dimensions: %zu\n", dim);
exit(EXIT_IMPOSSIBLE);
}
}
serial_val readValue(protozero::pbf_reader &pbf) {
serial_val sv;
sv.type = mvt_null;
sv.s = "null";
while (pbf.next()) {
switch (pbf.tag()) {
case 1:
sv.type = mvt_string;
sv.s = pbf.get_string();
break;
case 2:
sv.type = mvt_double;
sv.s = fpfmt::dtoa(pbf.get_double());
break;
case 3:
sv.type = mvt_double;
sv.s = std::to_string(pbf.get_uint64());
break;
case 4:
sv.type = mvt_double;
sv.s = std::to_string(-(long long) pbf.get_uint64());
break;
case 5:
sv.type = mvt_bool;
if (pbf.get_bool()) {
sv.s = "true";
} else {
sv.s = "false";
}
break;
case 6:
sv.type = mvt_string; // stringified JSON
sv.s = pbf.get_string();
if (sv.s == "null") {
sv.type = mvt_null;
}
break;
default:
pbf.skip();
}
}
return sv;
}
drawvec readPoint(std::vector<long long> &coords, size_t dim, double e) {
ensureDim(dim);
long long x, y;
projection->project(coords[0] / e, coords[1] / e, 32, &x, &y);
drawvec dv;
dv.push_back(draw(VT_MOVETO, x, y));
return dv;
}
drawvec readLinePart(std::vector<long long> &coords, size_t dim, double e, size_t start, size_t end, bool closed) {
ensureDim(dim);
drawvec dv;
std::vector<long long> prev;
std::vector<double> p;
prev.resize(dim);
p.resize(dim);
for (size_t i = start; i + dim - 1 < end; i += dim) {
if (i + dim - 1 >= coords.size()) {
fprintf(stderr, "Internal error: line segment %zu vs %zu\n", i + dim - 1, coords.size());
exit(EXIT_IMPOSSIBLE);
}
for (size_t d = 0; d < dim; d++) {
prev[d] += coords[i + d];
p[d] = prev[d] / e;
}
long long x, y;
projection->project(p[0], p[1], 32, &x, &y);
if (i == start) {
dv.push_back(draw(VT_MOVETO, x, y));
} else {
dv.push_back(draw(VT_LINETO, x, y));
}
}
if (closed && dv.size() > 0) {
dv.push_back(draw(VT_LINETO, dv[0].x, dv[0].y));
}
return dv;
}
drawvec readLine(std::vector<long long> &coords, size_t dim, double e, bool closed) {
return readLinePart(coords, dim, e, 0, coords.size(), closed);
}
drawvec readMultiLine(std::vector<long long> &coords, std::vector<int> &lengths, size_t dim, double e, bool closed) {
if (lengths.size() == 0) {
return readLinePart(coords, dim, e, 0, coords.size(), closed);
}
drawvec dv;
size_t here = 0;
for (size_t i = 0; i < lengths.size(); i++) {
drawvec dv2 = readLinePart(coords, dim, e, here, here + lengths[i] * dim, closed);
here += lengths[i] * dim;
for (size_t j = 0; j < dv2.size(); j++) {
dv.push_back(dv2[j]);
}
}
return dv;
}
drawvec readMultiPolygon(std::vector<long long> &coords, std::vector<int> &lengths, size_t dim, double e) {
ensureDim(dim);
if (lengths.size() == 0) {
return readLinePart(coords, dim, e, 0, coords.size(), true);
}
size_t polys = lengths[0];
size_t n = 1;
size_t here = 0;
drawvec dv;
for (size_t i = 0; i < polys; i++) {
size_t rings = lengths[n++];
for (size_t j = 0; j < rings; j++) {
drawvec dv2 = readLinePart(coords, dim, e, here, here + lengths[n] * dim, true);
here += lengths[n] * dim;
n++;
for (size_t k = 0; k < dv2.size(); k++) {
dv.push_back(dv2[k]);
}
}
dv.push_back(draw(VT_CLOSEPATH, 0, 0)); // mark that the next ring is outer
}
return dv;
}
struct drawvec_type {
drawvec dv{};
int type = 0;
};
std::vector<drawvec_type> readGeometry(protozero::pbf_reader &pbf, size_t dim, double e, std::vector<std::string> &keys) {
std::vector<drawvec_type> ret;
std::vector<long long> coords;
std::vector<int> lengths;
int type = -1;
while (pbf.next()) {
switch (pbf.tag()) {
case 1:
type = pbf.get_enum();
break;
case 2: {
auto pi = pbf.get_packed_uint32();
for (auto it = pi.first; it != pi.second; ++it) {
lengths.push_back(*it);
}
break;
}
case 3: {
auto pi = pbf.get_packed_sint64();
for (auto it = pi.first; it != pi.second; ++it) {
coords.push_back(*it);
}
break;
}
case 4: {
protozero::pbf_reader geometry_reader(pbf.get_message());
std::vector<drawvec_type> dv2 = readGeometry(geometry_reader, dim, e, keys);
for (size_t i = 0; i < dv2.size(); i++) {
ret.push_back(dv2[i]);
}
break;
}
default:
pbf.skip();
}
}
drawvec_type dv;
if (type == POINT) {
dv.dv = readPoint(coords, dim, e);
} else if (type == MULTIPOINT) {
dv.dv = readLine(coords, dim, e, false);
} else if (type == LINESTRING) {
dv.dv = readLine(coords, dim, e, false);
} else if (type == POLYGON) {
dv.dv = readMultiLine(coords, lengths, dim, e, true);
} else if (type == MULTILINESTRING) {
dv.dv = readMultiLine(coords, lengths, dim, e, false);
} else if (type == MULTIPOLYGON) {
dv.dv = readMultiPolygon(coords, lengths, dim, e);
} else {
// GeometryCollection
return ret;
}
dv.type = type / 2 + 1;
ret.push_back(dv);
return ret;
}
void readFeature(protozero::pbf_reader &pbf, size_t dim, double e, std::vector<std::string> &keys, struct serialization_state *sst, int layer, std::string layername, key_pool &key_pool) {
std::vector<drawvec_type> dv;
long long id = 0;
bool has_id = false;
std::vector<serial_val> values;
std::map<std::string, serial_val> other;
std::vector<std::shared_ptr<std::string>> full_keys;
std::vector<serial_val> full_values;
while (pbf.next()) {
switch (pbf.tag()) {
case 1: {
protozero::pbf_reader geometry_reader(pbf.get_message());
std::vector<drawvec_type> dv2 = readGeometry(geometry_reader, dim, e, keys);
for (size_t i = 0; i < dv2.size(); i++) {
dv.push_back(dv2[i]);
}
break;
}
case 11: {
static bool warned = false;
if (!warned) {
fprintf(stderr, "Non-numeric feature IDs not supported\n");
warned = true;
}
pbf.skip();
break;
}
case 12:
has_id = true;
id = pbf.get_sint64();
if (id < 0) {
static bool warned = false;
if (!warned) {
fprintf(stderr, "Out of range feature id %lld\n", id);
warned = true;
}
has_id = false;
}
break;
case 13: {
protozero::pbf_reader value_reader(pbf.get_message());
values.push_back(readValue(value_reader));
break;
}
case 14: {
std::vector<size_t> properties;
auto pi = pbf.get_packed_uint32();
for (auto it = pi.first; it != pi.second; ++it) {
properties.push_back(*it);
}
for (size_t i = 0; i + 1 < properties.size(); i += 2) {
if (properties[i] >= keys.size()) {
fprintf(stderr, "Out of bounds key: %zu in %zu\n", properties[i], keys.size());
exit(EXIT_IMPOSSIBLE);
}
if (properties[i + 1] >= values.size()) {
fprintf(stderr, "Out of bounds value: %zu in %zu\n", properties[i + 1], values.size());
exit(EXIT_IMPOSSIBLE);
}
full_keys.push_back(key_pool.pool(keys[properties[i]]));
full_values.push_back(values[properties[i + 1]]);
}
values.clear();
break;
}
case 15: {
std::vector<size_t> misc;
auto pi = pbf.get_packed_uint32();
for (auto it = pi.first; it != pi.second; ++it) {
misc.push_back(*it);
}
for (size_t i = 0; i + 1 < misc.size(); i += 2) {
if (misc[i] >= keys.size()) {
fprintf(stderr, "Out of bounds key: %zu in %zu\n", misc[i], keys.size());
exit(EXIT_IMPOSSIBLE);
}
if (misc[i + 1] >= values.size()) {
fprintf(stderr, "Out of bounds value: %zu in %zu\n", misc[i + 1], values.size());
exit(EXIT_IMPOSSIBLE);
}
other.insert(std::pair<std::string, serial_val>(keys[misc[i]], values[misc[i + 1]]));
}
values.clear();
break;
}
default:
pbf.skip();
}
}
for (size_t i = 0; i < dv.size(); i++) {
serial_feature sf;
sf.layer = layer;
sf.segment = sst->segment;
sf.has_id = has_id;
sf.id = id;
sf.tippecanoe_minzoom = -1;
sf.tippecanoe_maxzoom = -1;
sf.feature_minzoom = false;
sf.seq = *(sst->layer_seq);
sf.geometry = dv[i].dv;
sf.t = dv[i].type;
sf.full_keys = full_keys;
sf.full_values = full_values;
auto tip = other.find("tippecanoe");
if (tip != other.end()) {
json_pull_ptr jp = json_begin_string(tip->second.s.c_str());
json_object_ptr o = json_read_tree(jp);
if (o != nullptr) {
json_object *min = json_hash_get(o, "minzoom");
if (min != nullptr && (min->type == JSON_NUMBER)) {
sf.tippecanoe_minzoom = integer_zoom(sst->fname, fpfmt::dtoa(min->number()));
}
json_object *max = json_hash_get(o, "maxzoom");
if (max != nullptr && (max->type == JSON_NUMBER)) {
sf.tippecanoe_maxzoom = integer_zoom(sst->fname, fpfmt::dtoa(max->number()));
}
json_object *tlayer = json_hash_get(o, "layer");
if (tlayer != nullptr && (tlayer->type == JSON_STRING)) {
layername = tlayer->string();
}
}
}
serialize_feature(sst, sf, layername);
}
}
struct queue_run_arg {
size_t start;
size_t end;
size_t segment;
queue_run_arg(size_t start1, size_t end1, size_t segment1)
: start(start1), end(end1), segment(segment1) {
}
};
void *run_parse_feature(void *v) {
struct queue_run_arg *qra = (struct queue_run_arg *) v;
key_pool key_pool;
for (size_t i = qra->start; i < qra->end; i++) {
struct queued_feature &qf = feature_queue[i];
readFeature(qf.pbf, qf.dim, qf.e, *qf.keys, &(*qf.sst)[qra->segment], qf.layer, qf.layername, key_pool);
}
return NULL;
}
void runQueue() {
if (feature_queue.size() == 0) {
return;
}
std::vector<struct queue_run_arg> qra;
std::vector<pthread_t> pthreads;
pthreads.resize(CPUS);
for (size_t i = 0; i < CPUS; i++) {
*((*(feature_queue[0].sst))[i].layer_seq) = *((*(feature_queue[0].sst))[0].layer_seq) + feature_queue.size() * i / CPUS;
qra.push_back(queue_run_arg(
feature_queue.size() * i / CPUS,
feature_queue.size() * (i + 1) / CPUS,
i));
}
for (size_t i = 0; i < CPUS; i++) {
if (thread_create(&pthreads[i], NULL, run_parse_feature, &qra[i]) != 0) {
perror("pthread_create");
exit(EXIT_PTHREAD);
}
}
for (size_t i = 0; i < CPUS; i++) {
void *retval;
if (pthread_join(pthreads[i], &retval) != 0) {
perror("pthread_join");
}
}
// Lack of atomicity is OK, since we are single-threaded again here
long long was = *((*(feature_queue[0].sst))[CPUS - 1].layer_seq);
*((*(feature_queue[0].sst))[0].layer_seq) = was;
feature_queue.clear();
}
void queueFeature(protozero::pbf_reader &pbf, size_t dim, double e, std::vector<std::string> &keys, std::vector<struct serialization_state> *sst, int layer, std::string layername) {
struct queued_feature qf;
qf.pbf = pbf;
qf.dim = dim;
qf.e = e;
qf.keys = &keys;
qf.sst = sst;
qf.layer = layer;
qf.layername = layername;
feature_queue.push_back(qf);
if (feature_queue.size() > CPUS * 500) {
runQueue();
}
}
void outBareGeometry(drawvec const &dv, int type, struct serialization_state *sst, int layer, std::string layername) {
serial_feature sf;
sf.layer = layer;
sf.segment = sst->segment;
sf.has_id = false;
sf.tippecanoe_minzoom = -1;
sf.tippecanoe_maxzoom = -1;
sf.feature_minzoom = false;
sf.seq = (*sst->layer_seq);
sf.geometry = dv;
sf.t = type;
serialize_feature(sst, sf, layername);
}
void readFeatureCollection(protozero::pbf_reader &pbf, size_t dim, double e, std::vector<std::string> &keys, std::vector<struct serialization_state> *sst, int layer, std::string layername) {
while (pbf.next()) {
switch (pbf.tag()) {
case 1: {
protozero::pbf_reader feature_reader(pbf.get_message());
queueFeature(feature_reader, dim, e, keys, sst, layer, layername);
break;
}
default:
pbf.skip();
}
}
}
void parse_geobuf(std::vector<struct serialization_state> *sst, const char *src, size_t len, int layer, std::string layername) {
protozero::pbf_reader pbf(src, len);
size_t dim = 2;
double e = 1e6;
std::vector<std::string> keys;
while (pbf.next()) {
switch (pbf.tag()) {
case 1:
keys.push_back(pbf.get_string());
break;
case 2:
dim = pbf.get_int64();
break;
case 3:
e = pow(10, pbf.get_int64());
break;
case 4: {
protozero::pbf_reader feature_collection_reader(pbf.get_message());
readFeatureCollection(feature_collection_reader, dim, e, keys, sst, layer, layername);
break;
}
case 5: {
protozero::pbf_reader feature_reader(pbf.get_message());
queueFeature(feature_reader, dim, e, keys, sst, layer, layername);
break;
}
case 6: {
protozero::pbf_reader geometry_reader(pbf.get_message());
std::vector<drawvec_type> dv = readGeometry(geometry_reader, dim, e, keys);
for (size_t i = 0; i < dv.size(); i++) {
// Always on thread 0
outBareGeometry(dv[i].dv, dv[i].type, &(*sst)[0], layer, layername);
}
break;
}
default:
pbf.skip();
}
}
runQueue();
}